Communications power control

ABSTRACT

An outer loop power control method and apparatus for a radio communications system, for example a UMTS cellular radio communications system ( 60 ), comprising: determining that a plurality of different services are being communicated; performing a comparison with respect to the different services; and providing an inner loop power control performance target, for example a signal to interference ratio (SIR) target, in a manner dependent upon the comparison.

FIELD OF THE INVENTION

The present invention relates to power control in radio communicationssystems. The present invention relates in particular, but notexclusively, to outer loop power control in cellular communicationssystems, for example Universal Mobile Telecommunications System (UMTS)systems.

BACKGROUND OF THE INVENTION

Radio communications systems, for example cellular radio communicationssystems, are well known. In cellular radio communications systems,communication is carried out over radio links formed between basestations and subscriber units. A subscriber unit is typically a mobiletelephone (also known as a “mobile” or a “cell phone”).

Recently, cellular radio communications systems compliant with the wellknown Universal Mobile Telecommunications System (UMTS) standard havebeen implemented. In UMTS terminology, a base station is known as aNode-B, and a subscriber unit is known as a User Equipment (UE). UMTS isparticularly suitable for communicating both voice and data, includingso called multi-media data.

In radio communications systems, for example in cellular radiocommunications systems, power control is employed to attempt to avoidunnecessarily high levels of radio transmission power being used. Powercontrol may be employed to control the power level of transmission froma base station to a subscriber unit and/or from a subscriber unit to abase station. Broadly speaking, the power is adjusted to be sufficientlyhigh to meet a performance target or criterion, but no higher than isrequired to achieve this performance target or criterion.

In UMTS, the performance target employed in power control is that ofsignal to interference ratio (SIR). Power control is implemented bydetermining the SIR, usually at every timeslot (which in UMTS is every0.67 msec). The determined SIR is compared to a SIR target, and thepower level is adjusted accordingly. This is referred to as inner looppower control.

Some communications systems further implement outer loop power control.In outer loop power control, a further performance aspect is monitored.The value of the performance target used in the inner loop power controlis then varied according to the monitored level of the furtherperformance aspect. This variation is carried out at a less frequentrate than the inner loop power control assessments and adjustments. InUMTS, the further performance aspect may be chosen as any one of variousQuality of Service (QoS) parameters, but typically Frame Erasure Rate(FER) is used for voice communication and Block Error Rate (BLER) isused for data communication. In UMTS, the outer loop power control isimplemented such that the inner loop performance target is varied (orpotentially varied) every few hundred microseconds.

A further detail in relation to UMTS, and potentially other radiocommunications systems communicating differing types of data, e.g.multi-media, is that different types of data (i.e. different services)may require different values of the SIR target to be employed in theinner loop power control, due to differing quality of service needs. Forexample, a real-time video service may require a higher SIR than areal-time voice service due to more detail being required. Anotherexample is that any such real-time service may require a higher SIR thandata services that are not real-time, e.g. downloading of static webpages.

Conventionally, any conflict arising from these differing requirementshas not been considered or addressed.

SUMMARY OF THE INVENTION

The present inventors have realised that it would be desirable to modifythe conventional outer loop power control process when two or morediffering services are being communicated.

In a first aspect, the present invention provides an outer loop powercontrol method performed in a radio communications system, the methodcomprising: determining that a plurality of different services are beingcommunicated; performing a comparison with respect to the differentservices; and providing an inner loop power control performance targetin a manner dependent upon the comparison.

In a further aspect, the present invention provides an outer loop powercontrol method performed in a radio communications system, the methodcomprising: selecting one of a plurality of services being communicated;and providing the inner loop power control performance target of theselected service for use in an inner loop power control method for theservices. Selecting the one service may comprise selecting the servicewhich is the least delay tolerant service. Selecting the one service maybe based upon a comparison of one or more quality of servicecharacteristics or requirements of the services. Selecting the oneservice may comprise receiving an input from a user or operatorspecifying the service.

In a further aspect, the present invention provides an outer loop powercontrol method performed in a radio communications system, the methodcomprising: periodically calculating for each of a plurality ofdifferent services being communicated, a separate change to the currentinner power loop performance target; comparing the resulting respectivecurrent inner power loop performance target changes; identifying thelargest of the resulting respective current inner power loop performancetarget changes; and changing the current inner power loop performancetarget by the amount of the identified largest resulting respectivecurrent inner power loop performance target changes to arrive at theinner loop power control performance target being provided.

In a further aspect, the present invention provides an outer loop powercontrol method performed in a radio communications system, the methodcomprising: periodically calculating, for each of a plurality ofdifferent services, a separate new inner loop power control performancetarget value; comparing the resulting respective inner loop powercontrol performance target values; identifying the highest inner looppower control performance target value from among the resultingrespective inner loop power control performance target values; and usingthe identified highest inner loop power control performance target valueas the inner loop power control performance target being provided. Inthis aspect, the method may further comprise: determining that one ofthe resulting respective inner loop power control performance targetvalues differs from the resulting respective inner loop power controlperformance target value of one or more of the other services by morethan a predetermined threshold for more than a predetermined time; andresponsive thereto, adjusting rate matching parameters of one or more ofthe services to bring the differing respective inner loop power controlperformance target value closer to the resulting respective inner looppower control performance target values of the one or more otherservices.

In any of the above aspects, the inner loop power control performancetarget may be a signal to interference ratio, SIR, target.

In any of the above aspects, the radio communication system may be acellular radio communications system, and in particular may be a UMTSsystem.

In a further aspect, the present invention provides a storage mediumstoring processor-implementable instructions for controlling a processorto carry out the method of any of the above mentioned aspects.

In a further aspect, the present invention provides an apparatus forperforming an outer loop power control method in a radio communicationssystem, comprising: means for determining that a plurality of differentservices are being communicated; means for performing a comparison withrespect to the different services; and means for providing an inner looppower control performance target in a manner dependent upon thecomparison.

In a further aspect, the present invention provides an apparatus forperforming an outer loop power control method in a radio communicationssystem, comprising means for selecting one of a plurality of servicesbeing communicated; and means for providing the inner loop power controlperformance target of the selected service for use in an inner looppower control method for the services. The means for selecting the oneservice may comprise means for selecting the service which is the leastdelay tolerant service. The means for selecting the one service maycomprise means for basing the selection upon a comparison of one or morequality of service characteristics or requirements of the services. Themeans for selecting the one service may comprise means for receiving aninput from a user or operator specifying the service.

In a further aspect, the present invention provides an apparatus forperforming an outer loop power control method in a radio communicationssystem, comprising: means for periodically calculating, for each of aplurality of services being communicated, a separate change to thecurrent inner power loop performance target; means for comparing theresulting respective current inner power loop performance targetchanges; means for identifying the largest of the resulting respectivecurrent inner power loop performance target changes; and means forchanging the current inner power loop performance target by the amountof the identified largest resulting respective current inner power loopperformance target changes to arrive at the inner loop power controlperformance target being provided. The apparatus may further comprise:means for periodically calculating, for each of the services, a separatenew inner loop power control performance target value; the means forperforming a comparison with respect to the different services maycomprise means for comparing the resulting respective inner loop powercontrol performance target values; means for identifying the highestinner loop power control performance target value from among theresulting respective inner loop power control performance target values;and means for using the identified highest inner loop power controlperformance target value as the inner loop power control performancetarget being provided. The apparatus may further comprise: means fordetermining that one of the resulting respective inner loop powercontrol performance target values differs from the resulting respectiveinner loop power control performance target value of one or more of theother services by more than a predetermined threshold for more than apredetermined time; and means for adjusting, responsive thereto, ratematching parameters of one or more of the services to bring thediffering respective inner loop power control performance target valuecloser to the resulting respective inner loop power control performancetarget values of the one or more other services.

In each of the above mentioned apparatus, the inner loop power controlperformance target may be a signal to interference ratio, SIR, target.

Each of the above mentioned apparatus may be an element of a cellularradio communications system, in particular a UMTS system.

The present invention tends to alleviate or resolve conflict arisingfrom differing requirements with respect to outer loop power control ofdifferent services being communicated. The present invention tends toprovide an improved balance between quality of service requirement andoverall power consumption when different services are beingcommunicated.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic illustration of a cellular communications systemcompliant with, and containing network elements of, UMTS;

FIG. 2 is a block diagram of a communications unit;

FIG. 3 is a process flowchart showing a summary of the process stepscarried out in a first embodiment of the invention;

FIG. 4 is a process flowchart showing a summary of the process stepscarried out in a second embodiment of the invention;

FIG. 5 is a schematic illustration showing simplified plots of SIRtargets provided in the case of two services as a function of time;

FIG. 6 is a process flowchart showing a summary of the process stepscarried out in a third embodiment of the invention;

FIG. 7 is a schematic illustration showing further simplified plots ofSIR targets provided in the case of two services as a function of time;and

FIG. 8 is a process flowchart showing a summary of the process stepscarried out in a fourth embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a schematic illustration of a cellular communications system60 compliant with, and containing network elements of, UMTS.

A plurality of mobile stations, referred to under UMTS terminology asuser equipments (UE's) 62, 64, 66 communicate over radio links 18, 19,20, 21 with a plurality of base stations, referred to under UMTSterminology as Node-B's, 22, 24, 26, 28, 30, 32. The system comprisesmany other UE's and base stations, which for clarity are not shown. Inthis example each UE 62, 64, 66 is a mobile telephone equipped withmulti-media and internet browsing capability.

The Node-B's 22-32 are connected to external networks, for example, thepublic-switched telephone network (PSTN) or the Internet, 34 throughbase station controllers, referred to under UMTS terminology as RadioNetwork Controller stations (RNC), including the RNC's 36, 38, 40 andmobile switching centres (MSC's), such as MSC 42 (the others are, forclarity, not shown) and Serving GPRS Support Nodes (SGSN) such as SGSN44 (the others are, for clarity, not shown).

Each Node-B 22-32 contains one or more transceiver units andcommunicates with the rest of the cell-based system infrastructure viathe Iub interface 35 as defined in the UMTS specification.

Each RNC 36-40 may control one or more Node-B's 22-32. Each MSC 42provides a gateway to the external network 34, whilst the SGSN 44 linksto external packet networks.

The Operations and Management Centre (OMC) 46 is operably connected toRNC's 3640 and Node-B's 22-32 (shown only with respect to Node-B 26 andNode-B 28 for clarity), and administers and manages the parts of thecellular telephone communication system 60, as will be understood bythose skilled in the art.

In this embodiment, the Node-B's 22-32 and the UE's 62-66 have beenadapted, to offer, and provide for, an adapted form of outer loop powercontrol, as will be described in more detail below. More particularly,in this embodiment both the Node-B's 22-32 and the UE's 62-66 have beenadapted to implement the present invention, such that in this embodimentthe invention may be applied to both downlink (from Node-B to UE) anduplink (from UE to Node-B) transmissions. However, in other embodimentsthe invention may be applied by adapting just one of the types ofcommunications units (Node-B's or UE's).

More generally, the adaptation may be implemented in the respectivecommunications units in any suitable manner. For example, new apparatusmay be added to a conventional communications unit, or alternativelyexisting parts of a conventional communications unit may be adapted, forexample by reprogramming of a one or more processors therein. As suchthe required adaptation may be implemented in the form ofprocessor-implementable instructions stored on a storage medium, such asa floppy disk, hard disk, PROM, RAM or any combination of these or otherstorage media.

It is also within the contemplation of the invention that suchadaptation of transmission characteristics may alternatively becontrolled, implemented in full or implemented in part by adapting anyother suitable part of the communications system 60. For example, theRNC's 36-40 (pr equivalent parts in other types of systems) may beadapted to provide some or all of the implementation provided in thisembodiment by the Node-B's 22-30. Further, in the case of other networkinfrastructures, implementation may be at any appropriate node such asany other appropriate type of base station, base station controller etc.Alternatively the various steps involved in determining and carrying outsuch adaptation (as will be described in more detail below) can becarried out by various components distributed at different locations orentities within any suitable network or system.

As mentioned above, in this embodiment both the Node-B's 22-30 and UE's62-66 are adapted such that the invention may be applied in both uplinkand downlink direction. As such the following description will be madein terms of downlink transmission from Node-B 24 to UE 62 over radiolink 21, but it will be appreciated the description applies also touplink transmission from UE 62 to Node-B 24, and so on. Also, in thisembodiment Node-B 24 and UE 62 are of the same basic form with respectto aspects relevant to understanding this embodiment, and thus eachconstitute a basic communications unit 110 as illustrated in blockdiagram form in FIG. 2, and which will now be referred to in the furtherdescription of this embodiment.

Each communications unit 110 contains an antenna 202 coupled to a duplexfilter or circulator 204 that provides isolation between receive andtransmit chains within the communications unit 110.

The receiver chain, as known in the art, includes scanning receiverfront-end circuitry 206 (effectively providing reception, filtering andintermediate or base-band frequency conversion). The scanning front-endcircuit is serially coupled to a signal processing function 208.

An output from the signal processing function is provided to output 210.In the case of UE 62, output 210 includes a loudspeaker for audiooutput, a display and a data services output. In the case of Node-B 24,output 210 comprises interface means for communicating with RNC 38.

The receiver chain also includes received signal strength indicator(RSSI) circuitry 212, which in turn is coupled to a controller 214 thatoperates to maintain overall control of the different functions andmodules of the communications unit 110. The controller 214 is alsocoupled to the scanning receiver front-end circuitry 206 and the signalprocessing function 208 (generally realised by a digital signalprocessor, i.e. DSP).

The controller 214 includes a memory 216 that stores operating regimes,including those of interest with respect to this invention such ascoding and interleaving (when transmitting) and decoding (whenreceiving). The above mentioned storage medium may form part or all ofmemory 216.

A timer 218 is typically coupled to the controller 214 to control thetiming of operations (transmission or reception of time-dependentsignals) within the communications unit 110.

As regards the transmit chain, this includes an input 220. In the caseof UE 62, input 220 includes a microphone for a user's voice input, anda keyboard. In the case of Node-B 24, input 220 comprises interfacemeans for receiving communication from RNC 38. The input devices areeach coupled in series through transmitter/modulation circuitry 222 anda power amplifier 224 to the antenna 202. The transmitter/modulationcircuitry 222 and the power amplifier 224 are operationally responsiveto the controller.

The various components within each communications unit 110 are realisedin this embodiment in integrated component form. Of course, in otherembodiments, they may be realized in discrete form, or a mixture ofintegrated components and discrete components, or indeed any othersuitable form. Further, in this embodiment the controller 214 includingsome or all of memory 216, is implemented as a programmable processor,but in other embodiments can comprise dedicated circuitry or any othersuitable form (for example a part of memory 216 may be in RAM formintegrated with a processor, whereas a further part may be provided by afloppy disk or CD-RAM.

Certain details of the implementation of the inner loop and outer looppower control processes will now be described. First, the situation whenjust one service is being communicated will be described.

For the inner loop power control, the performance target employed isthat of signal to interference ratio (SIR). Power control is implementedby determining the SIR, usually at every timeslot (which in UMTS isevery 0.67 msec). The determined SIR is compared to a SIR target, andthe power level is adjusted accordingly. Thus, in terms of downlinktransmission from Node-B 24 to UE 62 over radio link 21, and consideringUE62 as constituted by communications unit 110, controller 214 assessesthe SIR for transmissions it receives from Node-B 24 against therelevant SIR target, and then transmits a resulting power controlinstruction (known as transmit power control, TPC) to the Node-B 24 suchthat Node-B 24 can then adjust its transmitted power accordingly.

Furthermore, by virtue of the outer loop power control, the value of theSIR target used by the UE 62 in the process described in the precedingparagraph is itself varied by controller 214 of UE 62. This variation iscarried out at a less frequent rate than the inner loop power controlassessments and adjustments, in this example every few hundredmicroseconds. The controller 214 of UE 62 monitors a further performanceaspect, and then determines changes in the SIR target dependent upon themonitored level of the further performance aspect, using an outer looppower control algorithm, such as the sawtooth algorithm.

In UMTS, the further performance aspect may be chosen as any one ofvarious Quality of Service (QoS) parameters, but typically Frame ErasureRate (FER) is used for voice communication and Block Error Rate (BLER)is used for data communication.

It is noted that corresponding features to those described above withrespect to communications unit 110 are also found in conventionalcommunications units (i.e. base stations and UE's). Likewise, the innerand outer loop power control processes described above are alsoimplemented in conventional communications units (i.e. base stations andUE's). However, communications unit 110 (i.e. Node-B 24 and UE 62)differ over conventional communications units by virtue that thecontroller 214, including memory 216, and where appropriate, the signalprocessing function 208 and the transmitter/modulation circuitry 222 isadapted to provide an adapted form of the outer loop power controlprocess, when plural services are being communicated (i.e. each of theplural services is carried on a respective transport channel of the samephysical channel), as will be described in more detail below.

In this first embodiment, when plural services are being communicated,only one outer loop power control algorithm, i.e. for one of theservices, is performed, and this provides the SIR target for use in theinner loop power control algorithm. The service whose SIR target is usedas the sole SIR target may be selected in various ways.

For example, the least delay tolerant of the services may be selected.

Another possibility is that the selection of the service may be basedupon a comparison of one or more quality of service characteristics orrequirements of the services.

Another possibility is that the service may be selected by a user of theUE 62 or an operator of part or all of the system 60. In this case, theUE 62 or system 60 receives an input from a user or operator specifyingthe service to be selected. The user or operator may be prompted tochoose, or otherwise chooses, to select the service he considers to bethe most important of the plural services according to his needs.

In this embodiment, the service selected is the least delay tolerantone, and hence the SIR target normally used for the selected least delaytolerant service is used as the SIR target for the outer loop powercontrol.

More generally, the selection of the service whose SIR target is used asthe sole SIR target may be made according to various possibilities,which may in general be specified according to the requirements of theparticular system or circumstances under consideration.

FIG. 3 is a process flowchart showing a summary of the process stepscarried out in this first embodiment by the UE 62 (for the presentaccount of power control as applied to the downlink transmission), whenthere are two services being communicated, e.g. a (first) speech serviceand a (second) data service. At step s2, the UE 62 determines the delaytolerance of the first service. At step s4, the UE 62 determines thedelay tolerance of the second service. At step s6, the UE 62 comparesthe determined delay tolerances and determines which is the least delaytolerant of the services. At step s8, the UE 62 sets and uses its SIRtarget as that normally used by the determined least delay tolerantservice. For power control as applied to the uplink transmission,corresponding process steps are performed by the Node-B 24 (or RNC 38).

A second embodiment will now be described. In this second embodiment,the same apparatus and processes as described for the first embodimentabove are employed, except where mentioned in the following.

In UMTS, a Time Transmission Interval (TTI) is defined, which is aperiod of coding and interleaving. The length of this will depend on theservice being communicated or provided, and will usually have a durationof one of 10 msec, 20 msec, 40 msec or 80 msec.

In this second embodiment, a single SIR target is initially set. At theend of each TTI, the block errors and quality estimates for each of theplural transport channels (each one carrying a respective one of theplural services) are used to determine a respective potential change inthe SIR target. Thus, for example, in the case of two services, at theend of each TTI, two different potential SIR target change values aredetermined, one derived from each service. Any suitable outer loop powercontrol algorithm may be used for this, e.g. a sawtooth algorithm. Thenthe plural (here, two) calculated potential SIR target changes arecompared, and the greater of the two is used as the actual SIR targetchange, i.e. the SIR target used in the inner power loop controlalgorithm over the course of the next TTI is changed by an amount equalto the greater of the two derived potential SIR target change values.This provides a process whereby the requirements of both services tendto be met or exceeded.

In other versions of this second embodiment, the respective potentialchanges in the SIR target may be determined at time intervals other thanat the end of each TTI. Such time intervals may be constant, or variedaccording to any suitable algorithm, and may be based upon TTI's or anyother suitable timing consideration.

FIG. 4 is a process flowchart showing a summary of the process stepscarried out in this second embodiment by the UE 62 (for the presentaccount of power control as applied to the downlink transmission), whenthere are two services being communicated, e.g. a (first) speech serviceand a (second) data service. At step s12, the UE 62 determines whetherthere are plural services being communicated. When the outcome is thatthere are not plural services, then this particular process is ended(although it will typically be repeated whenever the service status isdetected as changed by virtue of some other ongoing process). However,when the outcome is that there are indeed plural services, then theprocess moves to step s14. At step s14, the UE 62 identifies that thenext time interval is reached, i.e. in this embodiment that the TTI hasended. In this embodiment there are two services being communicated,hence at step s16, the UE 62 calculates a SIR target change for thefirst service and at step s18, the UE 62 calculates a SIR target changefor the second service. At step s20, the UE 62 compares the tworespective services' SIR target changes and determines which is thehighest. At step s22, the UE 62 provides the highest (here higher oftwo) SIR target change for use as the required change or increment inthe inner loop power control process, i.e. the highest of the determinedSIR target changes is provided for use in the inner loop power controlprocess where the inner loop power control SIR target is consequentlychanged by that amount. The process then returns to step s12, and so on,until it is determined on one of the repetitions of step s12 that thereare no longer plural services being communicated. (The actual use of thehighest SIR target change in the inner loop power control process is notshown as such in FIG. 4, as the timing of this is not necessarilyconsistent with the return to step s12 from step s22 in the processflowchart of FIG. 4.)

For power control as applied to the uplink transmission, correspondingprocess steps are performed by the Node-B 24 (or RNC 38).

Thus, in overview, in this second embodiment, a separate correction tothe SIR target is periodically, i.e. at time intervals, calculated foreach respective service. For each such time interval, the resultingrespective required SIR target changes are compared, and the highestchange is used as the overall derived correction to the SIR target fromthat time interval.

A third embodiment will now be described. In this third embodiment, thesame apparatus and processes as described for the first and secondembodiments above are employed, except where mentioned in the following.

In this third embodiment, a separate respective outer loop power controlalgorithm is performed for each of the plural services beingcommunicated. Thus plural outer loop power control algorithms are run inparallel. Consequently, after each calculation time interval of thealgorithms, a respective current SIR target will have been calculatedfor each service. FIG. 5 is a schematic illustration showing, by way ofexample, simplified plots of the SIR targets provided in the case of twoservices, namely a plot 301 of the SIR target calculated for the firstservice (data, say) and a plot 302 of the SIR target calculated for thesecond service (voice, say) as a function of time. As shown in FIG. 5,each of the plots is formed of values of the respective SIR targetsdetermined at consecutive time points t₀, t₁, t₂ . . . t₉, each of theseoccurring at the end of a time interval 304. In this embodiment, eachtime interval 304 is a TTI, and each time point t₀, t₁, t₂ . . . t₉, isat the end of a respective TTI. For clarity, the plots 301, 302 in FIG.5 are only shown over the course of nine time intervals 304, however itwill be appreciated that in normal operation there will be a very largenumber of time intervals over the course of, say, a typical call.

In this third embodiment, at each time point t₀, t₁, t₂ . . . t₉, therespective SIR targets of the different services are compared, and thehighest one is used as the SIR target, i.e. the value for the SIR targetused in the inner power loop control algorithm over the course of thenext ITI is the highest SIR target from amongst the respective SIRtargets determined for each service. In the example shown in FIG. 5, ascan be seen by comparing plot 301 of the SIR target of the first servicewith plot 302 of the SIR target of the second service, the SIR target ofthe first service is higher than the SIR target of the second servicefor time points t₀ to t₅ inclusive; whereas the SIR target of the secondservice is higher than the SIR target of the first service for timepoints t₆ to t₉ inclusive. Thus, in this example, the SIR target of thefirst service is used in the inner loop power control process as theoverall SIR target for time points t₀ to t₅, whereas the SIR target ofthe second service is used in the inner loop power control process asthe overall SIR target for time points t₆ to t₉.

As in the case of the earlier described second embodiment, this thirdembodiment provides a process whereby the requirements of both servicestend to be met or exceeded, but in comparison to the second embodimentprovides a further potential advantage of consuming less power than thesecond embodiment, since there will potentially be occasions when theSIR target is decremented in this third embodiment but would have beenincremented in the second embodiment.

In other versions of this third embodiment, the respective SIR targetsmay be determined at time intervals other than at the end of each TFI.Such time intervals may be constant, or varied according to any suitablealgorithm, and may be based upon TTI's or any other suitable timingconsideration.

FIG. 6 is a process flowchart showing a summary of the process stepscarried out in this third embodiment by the UE 62 (for the presentaccount of power control as applied to the downlink transmission), whenthere are two services being communicated, e.g. a (first) speech serviceand a (second) data service. At step s32, the UE 62 determines whetherthere are plural services being communicated. When the outcome is thatthere are not plural services, then this particular process is ended(although it will typically be repeated whenever the service status isdetected as changed by virtue of some other ongoing process). However,when the outcome is that there are indeed plural services, then theprocess moves to step s34. At step s34, the UE 62 identifies that thenext time interval is reached, i.e. in this embodiment that the ITI hasended. In this embodiment there are two services being communicated,hence at step s36, the UE 62 calculates a SIR target value for the firstservice and at step s38, the UE 62 calculates a SIR target value for thesecond service. At step s40, the UE 62 compares the two respectiveservices' SIR targets and determines which is the highest. At step s42,the UE 62 provides the highest (here higher of two) SIR target valuesfor use as the updated SIR target value in the inner loop power controlprocess, i.e. the highest of the determined SIR targets is provided foruse as the SIR target in the inner loop power control process. Theprocess then returns to step s12, and so on, until it is determined onone of the repetitions of step s12 that there are no longer pluralservices being communicated. (In practise, the UE 62 will typically alsoactually use the provided highest SIR target value as the SIR target inthe inner loop power control process, but this is not shown as such inFIG. 6 as the timing of this is not necessarily consistent with thereturn to step s32 from step s42 in the process flowchart of FIG. 6.)

For power control as applied to the uplink transmission, correspondingprocess steps are performed by the Node-B 24 (or RNC 38).

Thus, in overview, in this third embodiment, a separate new SIR targetvalue is periodically, i.e. at time intervals, calculated for eachrespective service. For each such time interval, the resultingrespective SIR targets are compared and the highest SIR target value isused as the overall new SIR target value from that time interval.

A fourth embodiment will now be described. In this fourth embodiment,the same apparatus and processes as described for the first, second andthird embodiments above are employed, except where mentioned in thefollowing.

This fourth embodiment is based on the above described third embodiment,but comprises a further adjustment stage, in which if it is determinedthat the calculated SIR target of any of the services is, over apredetermined amount of time, or predetermined number of time intervals,particularly high or low compared to the calculated SIR targets of theother services, for example the difference is greater than apredetermined threshold, then the rate matching parameters of one ormore of the services are adjusted to bring the particularly high or lowSIR target and the SIR targets of the other services closer together.

A situation where this may be applied is for the case of the SIR targetsprovided according to the method of the third embodiment above if theirvalues with time are found to be of, say, a form as shown schematicallyin FIG. 7. FIG. 7 is a schematic illustration showing, by way of anotherexample, further simplified plots of the SIR targets provided in thecase of two services. FIG. 7 uses the same reference numerals toidentify the same features as were used in FIG. 5.

In the example of FIG. 7, the plot 302 of the SIR target calculated forthe second service is higher than plot 301 of the SIR target calculatedfor the first service by more than a predetermined threshold 401 overthe course of a predetermined number of TTI time intervals 304, which inthis simplified example is nine time intervals. (In practical systems,rather than this simplified example, the number of time intervalsrequired to be satisfied will typically be much higher than this, andwill be specified or selected, along with the difference threshold 401,by the skilled practitioner according to the requirements of theparticular system or circumstances under consideration.) This impliesthat the quality of service of the second service may be better than itneeds to be, with unnecessarily high consumption of power. Thepower/performance balance is potentially improved by the followingprocess carried out in this fourth embodiment.

In response to the difference between the respective SIR targets of thetwo services being more than a predetermined threshold for more than apredetermined time, the rate matching parameters of both services arealtered, to bring the respective SIR targets closer together. Inparticular, repetition is added to the first service, and puncturing isadded to the second service. This may be implemented in any suitablefashion, although in this embodiment this is conveniently implementedmid-call using existing messages known as Radio Resource Control (RRC)message Transport Channel Reconfigure. (In other versions of thisembodiment, the adjustment comprises only either repetition being addedto the first service or puncturing being added to the second service. Inthe case of more than two services, any combination of adding repetitionto one or more of the services with relatively lower SIR target, and/oradding puncturing to one or more of the services with relatively higherSIR target may be employed.)

More generally, in other versions of this fourth embodiment, theadjustment may be triggered by comparison of an average differencebetween the SIR targets of plural services over a given time to thepredetermined difference threshold.

Furthermore, the above described monitoring of the differential withrespect to the predetermined threshold 401 may be carried out at alltimes, or triggered by any predetermined event or parameter values asrequired. One particular possibility is to trigger this process when theprocess described for the third embodiment above continues for a givenamount of time or number of time intervals without the respective plotsof the SIR targets of the two services “crossing over”, i.e. changingwith respect to which is the higher value (or in the case of more thantwo services, when the plot of the SIR target of one service does notcross over any of the plots of the other services during a given amountof time or number of time intervals).

FIG. 8 is a process flowchart showing a summary of the process stepscarried out in this fourth embodiment by the UE 62 (for the presentaccount of power control as applied to the downlink transmission), whenthere are two services being communicated, e.g. a (first) speech serviceand a (second) data service. Steps s32, s34, s36, s38, s40 and s42 areas described above for the third embodiment.

In addition, after step s40, at step s50, the difference between the SIRtargets of the two services is compared to a criterion or criteria. Inthis example, the criteria are that the difference in the SIR targets atthis time interval 304 is greater than the predetermined threshold 401,and that this is the ninth consecutive time interval 304 for which thisis the case. If these criteria are not met, then the process moves tostep s42. However, if these criteria are met, then the process moves tostep s52. At step s52, the UE 62 provides (internal) adjustmentinstructions for adjusting the rate matching parameters on the firstservice and/or the second service. In this example, the adjustmentinstructions are for adding repetition to the first service and addingpuncturing to the second service. The process then moves on to step s42.(In practise, the UE 62 will typically also actually implement theprovided adjustment instructions, but this is not shown as such in FIG.8, as the timing of this is not necessarily consistent with the returnto step s32 from step s42 in the process flowchart of FIG. 6.)

For power control as applied to the uplink transmission, correspondingprocess steps are performed by the Node-B 24 (or RNC 38).

In the flowcharts of FIGS. 4, 6 and 8, all process steps are shown (anddescribed in the corresponding part of the description) as beingimplemented one after the other, but it will be appreciated that many ofthe steps, for example step s2 and step s4 in FIG. 3, step s16 and steps18 in FIG. 4, and step s36 and step s38 in FIG. 6 and FIG. 8, may beperformed at the same time in parallel or in some other overlappingmanner.

Although in certain of the above embodiments the number of differentservices is two, it will be appreciated that the invention is applicableto pluralities of services comprising more than two services. Also, inthe case of two or more services, one of the services of the pluralityof services may in fact be a signalling channel.

In the above embodiments the inner loop power control performance targetis a SIR target, but in other embodiments other performance targets maybe employed.

The above embodiments are implemented in a cellular radio communicationssystem, more particularly a UMTS system, in which inner loop powercontrol and outer loop power control are defined in the UMTS standardsand are well known to the skilled person. However, other embodiments maybe implemented in other types of cellular radio communications systems,and more generally in other types of radio communications systems, whichhave inner loop power control and outer loop power control. The terms“inner loop power control” and “outer loop power control” are to beunderstood to extend, as appropriate in the case of radio communicationssystems other than UMTS, to any power control arrangements, processes oralgorithms in which a first parameter or plurality of parameters orfunction is assessed against a target on a first timescale to determinepossible power changes (i.e. inner loop power control) and where thetarget itself is adjusted in view of a second parameter or plurality ofparameters or function on a second timescale longer than the firsttimescale (i.e. outer loop power control), even if such power controlaspects are not called “inner loop” and “outer loop” as such in theterminology usually used for such systems.

1. An outer loop power control method performed in a radiocommunications system, the method comprising: determining that aplurality of different services are being communicated; performing adelay tolerance comparison with respect to the different services;selecting the service having the least delay tolerant service; andproviding an inner loop power control performance target of the selectedservice in a manner dependent upon the delay tolerance comparison. 2-3.(canceled)
 4. A method according to claim 1, wherein selecting one ofthe services is also performed based upon a comparison of one or morequality of service characteristics or requirements of the services.
 5. Amethod according to claim 1, wherein selecting one of the servicescomprises receiving an input from a user or operator specifying theservice.
 6. A method according to claim 1, further comprising:periodically calculating, for each of the services, a separate change tothe current inner power loop performance target; wherein performing acomparison with respect to the different services comprises comparingthe resulting respective current inner power loop performance targetchanges; identifying the largest of the resulting respective currentinner power loop performance target changes; and changing the currentinner power loop performance target by the amount of the identifiedlargest resulting respective current inner power loop performance targetchanges to arrive at the inner loop power control performance targetbeing provided.
 7. A method according to claim 1, further comprising:periodically calculating, for each of the services, a separate new innerloop power control performance target value; wherein performing acomparison with respect to the different services comprises comparingthe resulting respective inner loop power control performance targetvalues; identifying the highest inner loop power control performancetarget value from among the resulting respective inner loop powercontrol performance target values; and using the identified highestinner loop power control performance target value as the inner looppower control performance target being provided.
 8. A method accordingto claim 7, further comprising: determining that one of the resultingrespective inner loop power control performance target values differsfrom the resulting respective inner loop power control performancetarget value of one or more of the other services by more than apredetermined threshold for more than a predetermined time; responsivethereto, adjusting rate matching parameters of one or more of theservices to bring the differing respective inner loop power controlperformance target value closer to the resulting respective inner looppower control performance target values of the one or more otherservices.
 9. A method according to claim 1, wherein the inner loop powercontrol performance target also includes a signal to interference ratio,SIR, target.
 10. A method according to claim 1, wherein the radiocommunication system is a cellular radio communications system.
 11. Amethod according to claim 10, wherein the cellular radio communicationssystem is a UMTS system.
 12. (canceled)
 13. An apparatus for performingan outer loop power control method in a radio communications system,comprising: means for determining that a plurality of different servicesare being communicated; means for performing a delay tolerancecomparison with respect to the different services; means for selectingthe service having the least delay tolerant service; and means forproviding an inner loop power control performance target in a mannerdependent upon the delay tolerance comparison. 14-15. (canceled)
 16. TheApparatus according to claim 13, wherein the means for selecting one ofthe services also comprises means for basing the selection upon acomparison of one or more quality of service characteristics orrequirements of the services.
 17. The Apparatus according to claim 13,wherein the means for selecting one of the services comprises means forreceiving an input from a user or operator specifying the service. 18.The Apparatus according to claim 13, further comprising: means forperiodically calculating, for each of the services, a separate change tothe current inner power loop performance target; wherein the means forperforming a comparison with respect to the different services comprisesmeans for comparing the resulting respective current inner power loopperformance target changes; means for identifying the largest of theresulting respective current inner power loop performance targetchanges; and means for changing the current inner power loop performancetarget by the amount of the identified largest resulting respectivecurrent inner power loop performance target changes to arrive at theinner loop power control performance target being provided.
 19. TheApparatus according to claim 13, further comprising: means forperiodically calculating, for each of the services, a separate new innerloop power control performance target value; wherein the means forperforming a comparison with respect to the different services comprisesmeans for comparing the resulting respective inner loop power controlperformance target values; means for identifying the highest inner looppower control performance target value from among the resultingrespective inner loop power control performance target values; and meansfor using the identified highest inner loop power control performancetarget value as the inner loop power control performance target beingprovided.
 20. The Apparatus according to claim 19, further comprising:means for determining that one of the resulting respective inner looppower control performance target values differs from the resultingrespective inner loop power control performance target value of one ormore of the other services by more than a predetermined threshold formore than a predetermined time; means for adjusting, responsive thereto,rate matching parameters of one or more of the services to bring thediffering respective inner loop power control performance target valuecloser to the resulting respective inner loop power control performancetarget values of the one or more other services.
 21. The Apparatusaccording to claim 13, wherein the inner loop power control performancetarget also includes a signal to interference ratio, SIR, target. 22-25.(canceled)